This will result in a neat little test failure instead of an
unreadable thirty-line traceback when the test fails.
Change-Id: Ie0b564a95586d72eb730ab8a70a6175eb3ae743d
Add the LessFileCompilationTest test case class, which represents the
validation of a LESS file by compilation.
Add the LessTestSuite test suite, which tests all LESS files registered
with the ResourceLoader, and use this to rewrite the checkLess.php
maintenance script.
Bug: 54665
Change-Id: Iedb8dc31e4817d8b4e40b655cf9b8fb092979e90